Conventionally, a theft-preventing apparatus has been developed for preventing a theft of a vehicle, parts of a vehicle or an attachment of a vehicle. The theft-preventing apparatus prevents a theft by generating an alarm such as a horn or prohibiting a start of the vehicle when the theft-preventing apparatus detects that an unauthorized person intrudes into the vehicle.
Japanese Laid-Open Patent Application No.4-197853 discloses such a theft-preventing apparatus. This theft-preventing apparatus enters a waiting mode and starts blinking a display apparatus when doors of a vehicle is detected to be locked. In the waiting mode, an alarm is not generated even if the doors are unlocked by means other than a key. Thereby, an alarm is prevented from being generated when a passenger remains in the vehicle unlocks a door from inside the vehicle so as to get off from the vehicle after the door was locked. The waiting state is continued for a predetermined time period. After the predetermined time period is elapsed, the theft-preventing apparatus shifts from the waiting state to a cautioning state. In the cautioning state, an alarm signal is generated by providing a drive signal to a horn or a lamp when it is detected that one of the doors is opened by means other than the key or a posture of the vehicle is changed. Additionally, caution is given to a person who attempts a theft so as to provided an effect to prevent a theft by continuously blinking the display apparatus in the cautioning state. In the above-mentioned conventional theft-preventing apparatus, a blinking period of the display apparatus is changed between the waiting state and the cautioning state, and, thereby, it is possible to distinguish the cautioning state from the waiting state.
As a vehicle theft-preventing apparatus different from the above-mentioned conventional theft-preventing apparatus, for example, an apparatus (referred to as an immobilizer apparatus) for preventing a start of an engine by a key other than a correct key is known. The immobilizer apparatus previously provides a key code and a registered code to a key and a vehicle, respectively. A start of the engine is permitted only when the key code matches the registered code. Thus, according to the immobilizer apparatus, it is difficult to start a vehicle without using the correct key, and, thereby, the vehicle is prevented from being theft.
The immobilizer apparatus is set to the cautioning state in which a start of the engine is prohibited at the time when the key is removed from an ignition-key cylinder. When the immobilizer apparatus is in the cautioning state, the owner of the vehicle is notified that the apparatus is normally operated. At the same time, a display such as blinking of the display apparatus is performed so as to give a caution to a thief.
As mentioned above, the immobilizer apparatus has the same purpose as the above-mentioned conventional theft-preventing apparatus with respect to prevention of theft of a vehicle. Accordingly, when both the above-mentioned conventional theft-preventing apparatus and the immobilizer apparatus are provided to the same apparatus, time periods of the waiting states of these apparatuses are substantially equal to each other. Accordingly, there may be no problem if displays indicating operational states of these theft-preventing apparatuses are common to each other.
However, since the above-mentioned conventional theft-preventing apparatus does not consider common use with the immobilizer apparatus, an exclusive display apparatus must be provided other than that of the immobilizer apparatus. That is, the above-mentioned theft-preventing apparatus has a problem in that a number of parts is increased since a display apparatus must be provided for each theft-preventing apparatus when the theft-preventing apparatus is provided together with other theft-preventing apparatuses.